Air-Filled Balloon Motor

I have an idea for a small motor/fan that can attach to an air-filled balloon (not helium) to project the balloon into the air as if it's floating. I feel with the advent of all of the micro motors that exist for small radio controlled flying objects and other items that a fan/motor could exist that could elevate a regular air-filled balloon off of the ground. Although I'm not an engineer, I do have a few concerns surrounding the idea: If it's physically possible to make such a motor, it needs to be able to stay afloat or in the air for a very long time - preferably throughout an entire day if possible. Needing to recharge a battery in this product every 10-15 minutes simply wouldn't be efficient nor useful. Therefore, can it be made so that it can in fact float for a long period of time? If a motor can be designed or used for this purpose, if the balloon is attached to some sort of anchoring string, will it be able to elevate or float in a nearly straight-up motion? Not accounting for wind or other elements, the motor itself would be most useful if it could project the balloon straight up. The cost would need to be relatively inexpensive, due to the usefulness of the product. When looking at something like an r/c "Air Hogs" product, you can purchase this completely assembled product off the retail shelf for about $40, including a radio to control it, plus all of the other parts (minus replaceable batteries). Therefore, one small motor from inside this kit should be very inexpensive. The motor shouldn't require any controlling mechanism in my opinion, as once attached to the balloon and anchoring string it should simply fly straight up until the end of the anchoring string is reached/completely stretched out. I wouldn't want a need to control steering or speed. It should likely just have an on/off switch. The fan/motor would need to be enclosed inside a plastic or other material that was covered with some sort of guard or protective slats to help protect against small fingers from entering the blade area. Although I'm thinking the entire product would be a lightweight plastic, it needs to be safe for a wide range of ages.